d2074daebe
The Windows documentation insists that every WSAStartup call should have a matching WSACleanup call. However, if that ever had actual relevance, it wasn't in this century. Every remotely-modern Windows kernel is capable of cleaning up when a process exits without doing that, and must be so to avoid resource leaks in case of a process crash. Moreover, Postgres backends have done WSAStartup without WSACleanup since commit 4cdf51e64 in 2004, and we've never seen any indication of a problem with that. libpq's habit of doing WSAStartup during connection start and WSACleanup during shutdown is also rather inefficient, since a series of non-overlapping connection requests leads to repeated, quite expensive DLL unload/reload cycles. We document a workaround for that (having the application call WSAStartup for itself), but that's just a kluge. It's also worth noting that it's far from uncommon for applications to exit without doing PQfinish, and we've not heard reports of trouble from that either. However, the real reason for acting on this is that recent experiments by Alexander Lakhin show that calling WSACleanup during PQfinish is triggering the symptom we occasionally see that a process using libpq fails to emit expected stdio output. Therefore, let's change libpq so that it calls WSAStartup only once per process, during the first connection attempt, and never calls WSACleanup at all. While at it, get rid of the only other WSACleanup call in our code tree, in pg_dump/parallel.c; that presumably is equally useless. Back-patch of HEAD commit 7d00a6b2d. Discussion: https://postgr.es/m/ac976d8c-03df-d6b8-025c-15a2de8d9af1@postgrespro.ru
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.